Partitioning between atmospheric deposition and canopy microbial nitrification into throughfall nitrate fluxes in a Mediterranean forest
Microbial activity plays a central role in nitrogen (N) cycling, with effects on forest productivity. Although N biotransformations, such as nitrification, are known to occur in the soil, here we investigate whether nitrifiers are present in tree canopies and actively process atmospheric N.This stud...
| Autores: | , , , , , , , , , |
|---|---|
| Tipo de recurso: | artículo |
| Fecha de publicación: | 2020 |
| País: | España |
| Institución: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/447095 |
| Acceso en línea: | https://hdl.handle.net/2117/447095 https://dx.doi.org/10.1111/1365-2745.13288 |
| Access Level: | acceso abierto |
| Palabra clave: | Ammonia-oxidizing archaea Ammonia-oxidizing bacteria Canopy nitrification Mediterranean forest Metabarcoding Nitrate fluxes Stable isotopes Throughfall Àrees temàtiques de la UPC::Enginyeria agroalimentària::Ciències forestals |
| Sumario: | Microbial activity plays a central role in nitrogen (N) cycling, with effects on forest productivity. Although N biotransformations, such as nitrification, are known to occur in the soil, here we investigate whether nitrifiers are present in tree canopies and actively process atmospheric N.This study was conducted in a Mediterranean holm oak (Quercus ilex L.) forest in Spain during the transition from hot dry summer to cool wet winter. We quantified —N and —N fluxes for rainfall (RF) and throughfall (TF) and used d15N, d18O and ¿17O to elucidate sources of . Finally, we characterized microbial communities and abundance of nitrifiers on foliage, RF and TF water through metabarcoding and quantitative polymerase chain reaction respectively.NO3—N fluxes at the site were larger in TF than RF, suggesting a contribution from dry deposition, as also supported by d15N and d18O. However, ¿17O indicated that about 20% of in TF derived from canopies nitrification in August, after a severe drought, with a lower proportion in September (˜8%). This seasonal partitioning between biologically and atmospherically derived coincided with a decreasing trend of the abundance of archaeal nitrifiers. Tree canopies and TF had more diverse microbial communities than RF. Yet, RF showed higher variability in microbial composition, likely associated with the origin of air masses.Synthesis. Atmospheric N deposition is significantly altered after passing through tree canopies. While nitrification has been proposed as one of the mechanisms responsible for these changes, very few studies directly investigate its occurrence. Here, we showed that nitrification by epiphytic leaf microbes contributed to increasing NO3 in TF and that nitrifiers' activity was reduced going from the dry and hot summer to the cool winter. Overall, these results highlight the power of coupling microbial community analysis, functional gene amplification and stable isotope approaches to examine ecosystem-scale processes |
|---|